1. Field of the Invention
The present invention relates to a non-contact information device capable of reading and writing information in a non-contact manner, and in particular, to an RF-ID tag or a non-contact IC card having a sensor and accumulating the values detected by the sensor.
2. Description of the Related Art
A battery-fed RF-ID, i.e. an active RF-ID tag is mounted on a commodity or carried by a person to transmit a RF signal of a predetermined frequency carrying the ID and the information on the commodity or the person, as the case may be. The RF signal of the RF-ID tag is read by a reader. The information thus read is further processed by a computer or the like. In this way, the distribution of the commodity or the behavior of the person, as the case may be, can be monitored and managed. The battery-fed active RF-ID tag, as compared with the passive RF-ID tag for receiving the power from a reader/writer in a non-contact manner, has a comparatively long communicable distance and high practical value.
The RF-ID tag having a sensor for both detecting the physical quantity in the surrounding environment and accumulating the data of the detection values is read by the reader/writer, so that the detection value data can be collected together with the ID.
Japanese Patent Application Laid-Open No. 2000-113130 (A) dated Apr. 21, 2000 discusses an IC tag detection system of low power consumption. This system includes a communication circuit, a control unit, a power supply unit for supplying power to these parts from a battery, time counting means, plural IC tags set at predetermined different transmission timings, and a sensor for detecting the presence or absence of the respective IC tags based on the communication with them. The sensor has a communication circuit for judging and detecting the reception for each set time of the IC tags as required. In the absence of an inquiry from the sensor, the IC tag can avoid the wasteful reaction or battery power consumption.
Japanese Patent Application Laid-Open No. 2001-251210 (A) dated Sep. 14, 2001 discusses a method of realizing a frequency lock requiring no independent reference oscillators for the transmitters of two nodes in the duplex link. In the full duplex link, the carrier frequencies of the transmitters are tuned using the information of the receiving frequency to thereby lock the transmission frequencies of the two nodes in the link at the same time. The offset in the carrier frequency of the first transmitter is detected as a corresponding offset of the second receiver. The second receiver shifts the carrier frequency of the first transmitter in accordance with the detected offset and thus notifies the detected offset to the first transmitter. The carrier frequency of the first transmitter is corrected by the offset detected in the first receiver.
Japanese Patent Application Laid-Open No. 2001-187611 dated Jul. 10, 2001 discusses a temperature management system including a sensor unit having a temperature sensor in the ID tag. The CPU of the sensor unit writes in the EEPROM (Electrically Erasable Programmable Read Only Memory) the temperature measured by the temperature sensor at predetermined intervals of time. The temperature data written in the EEPROM can be read by an external reader/writer. This ID tag with a sensor, if mounted on a beer barrel, for example, makes it possible to detect the temperature change of the beer barrel before the beer is sold to customers in outlets such as restaurants after shipment from a beer brewery. In this way, the beer temperature can be managed sufficiently.
Japanese Patent Application Laid-Open No. 2005-87135 dated Apr. 7, 2005 discusses a food cooking history measurement method. This method uses an RF-ID having at least a temperature sensor, a timer and a RAM for recording, in time series, the values measured by the temperature sensor. With this RF-ID, the internal data of the food material measured in the cooking environment with the temperature sensor inserted therein is recorded in the RAM 14.
Japanese Patent Application Laid-Open No. 2006-127162 dated May 18, 2006 discusses a measurement data collection system, in which a measuring instrument transmits the measurement data to the IC tag by radio, and the IC tag that has received the measurement data stores the particular data. The IC tag reader transmits the data to the IC tag reader by radio either periodically or with the reception of a start signal from the gate as a motive. The user collects the measurement data in the measurement data collection server 4 on the network without wired connection.